Silver halide supersensitized photographic emulsion

ABSTRACT

A silver halide photographic emulsion containing at least one sensitizing dye represented by the following formula I:   wherein R1 is an alkyl group having from one to four carbon atoms; R2 and R3 are individually selected from the group consisting of an alkyl group, an allyl group and an alkyl group substituted by a hydroxyl group, an alkoxyl group, a carboxyl group, a sulfo group, a carboxyalkoxyl group or a sulfoalkoxyl group; Z1 and Z2 are the same or different atomic groups necessary to complete a benzothiazole nucleus of a benzoselenazole nucleus; n is 1 or 2 and X is an acid anion group; and at least one sensitizing dye represented by the following formula II:   wherein A is a thienyl group, a furyl group or a thienyl group substituted by a halogen atom, an alkyl group or an alkylcarboxyl group; R4 and R5 are individually selected from the group consisting of an alkyl group, an aryl group and an alkyl group substituted by a hydroxyl group, an alkoxyl group, a carboxyl group, a sulfo group, a carboxyalkoxyl group or a sulfoalkoxyl group; at least one of R4 and R5 being a sulfosubstituted alkyl group; Z3 is an atomic group necessary to complete a naphthothiazole nucleus or a naphthoselenazole nucleus, and Z4 is an atomic group necessary to complete a naphthothiazole nucleus, a naphthoselenazole nucleus, a benzothiazole nucleus or a benzoselenazole nucleus.

United States Patent [72] Inventors Keisuke Shiba;

Akira Sato, both of Kanagawa, Japan [21] Appl. No. 27,035

[22] Filed Apr. 9, 1970 [45] Patented Jan. 4, 1972 [73] Assignee FujiPhoto Film Co., Ltd.

Kanagawa, Japan [32] Priority Apr. 9, 1969 [33] Japan [54] SILVER HALIDESUPERSENSITIZED PHOTOGRAPI-IIC EMULSION 11 Claims, 1 Drawing Fig.

[52] U.S. CI 96/123, 96/124, 96/127, 96/137 [51] Int. Cl G03c H28 [50]Field of Search 96/123, 124

[56] References Cited UNITED STATES PATENTS 2,704,720 3/1955 Jones96/123 3,432,303 3/1969 Jones et a1. .1 96/124 Primary ExaminerJ, TravisBrown Attorney-Sughrue, Rothwell, Mion, Zinn & Macpeak ABSTRACT: Asilver halide photographic emulsion containing at least one sensitizingdye represented by the following wherein R is an alkyl group having fromone to four carbon atoms; R and R are individually selected from thegroup consisting of an alkyl group, an allyl group and an alkyl groupsubstituted by a hydroxyl group, an alkoxyl group, a carboxyl group, asulfo group, a carboxyalkoxyl group or a sulfoalkoxyl group; Z and Z arethe same or different atomic groups necessary to complete abenzothiazole nucleus of a benzoselenazole nucleus; n is 1 or 2 and X isan acid anion group; and at least one sensitizing dye represented by thefollowing formula 11:

z, CCH=CCH==C z.

I 1 R4 R5 wherein A is a thienyl group, a furyl group or a thienyl groupsubstituted by a halogen atom, an alkyl group or an alkylcarboxyl group;R, and R are individually selected from the group consisting of an alkylgroup, an aryl group and an alkyl group substituted by a hydroxyl group,an alkoxyl group, a carboxyl group, a sulfo group, a carboxyalkoxylgroup or a sulfoalkoxyl group; at least one of R and R being asulfosubstituted alkyl group; Z is an atomic group necessary to completea naphthothiazole nucleus or a naphthoselenazole nucleus, and Z is anatomic group necessary to complete a naphthothiazole nucleus, anaphthoselenazole nucleus, a benzothiazole nucleus or a benzoselenazolenucleus.

PATENTEDJAN 4m 3,632,349

WAVE LENGTH INVENTORS KEISUKE SHIBA AKIRA SATO SILVER HALIDESUPERSENSITIZED PHOTOGRAPHIC EMULSION BACKGROUND OF THE INVENTION 1.Field of the Invention This invention relates to a spectrally sensitizedsilver halide photographic emulsion and more particularly, to anemulsion whose spectral sensitivity in the red region is raised by theuse of a combination of at least two kinds of sensitizing dyes.

2. Description of the Prior Art It has long been known that, in order toextend the light-sensitive wavelength region of a light-sensitivematerial further to the long wavelength side, one adds some sensitizingdye to the silver halide emulsion. This is termed spectralsensitization. The spectral sensitization effect depends upon thechemical structure of the sensitizing dye employed, its state inemulsion and various properties of the emulsion such as the crystalhabit of the silver halide, the halogen composition, the silver ionconcentration and the hydrogen ion concentration. It is also affected byfog inhibitors coexistent in the emulsion, stabilizers, flocculatingagents, hardeners, binders and plasticizers.

In the case of a color sensitive material of the incorporated type,particularly those in which a coupler is incorporated, these additivesoften act so as to lower the spectral sensitivity, In manylight-sensitive materials, two or more sensitizing dyes are used inorder to sensitize to a predetermined wavelength region according totheir use. In many cases, however, the sensitization produced by the useof two or more sensitizing dyes is less than the sum of thesensitizations of the components. This is known as antisensitization. Onthe other hand, sometimes the use of two or more sensitizing dyes inspecial combination gives a sensitization greater than the sum of theindividual effects. This is known as supersensitization. A severeselection is required for such a combination of two or more sensitizingdyes having a supersensitizing action. Since even a slight difference inchemical structure has a large effect on the supersensitization, it is aview common to all photographic engineers that a combination ofsensitizing dyes showing supersensitizing action cannot readily beexpected from the chemical structure only of the dyes. It has been verydifficult to find a combination of two or more sensitizing dyes showinga supersensitizing action.

A color sensitive material is ordinarily composed of at least threelight-sensitive emulsion layers: a blue-sensitive emulsion layer, agreen-sensitive emulsion layer and a red-sensitive emulsion layer. Thedistribution of spectral sensitivity of each emulsion layer is aprincipal factor in determining the color reproduction characteristicsof the light-sensitive material. In order to obtain a suitable colorreproduction, in general, the spectral light-sensitive wavelengthregions of the blue, green and red-sensitive emulsion layers,respectively, must be separated sufficiently. Above all, thered-sensitive emulsion must have a high sensitivity in the red regionand a low sensitivity in the green region, because a dye sensitizingthroughout the whole visible region is generally used therefor. In orderto obtain a true color reproduction, the maximum sensitizing wavelengthshould be within a range of from 640 to 650 my. and the sensitivity oflonger wavelengths should be up to at least 690 mp. to which the visiblesensitivity extends. Moreover, the sensitizing dye used in thered-sensitive emulsion layer must be prevented from diffusing intoanother adjacent emulsion layer and sensitizing the same. In the case ofa high sensitivity color light-sensitive material, care should be takento avoid the lowering of a high spectral sensitivity with the passage oftime and while being allowed to stand in a state of liquid emulsion.

It is therefore an object of the present invention to provide a silverhalide emulsion wherein the maximum sensitizing wavelength is not longerthan 650 mu, the spectral sensitivity extends to 680 to 690 my. in a lowsensitivity and the red sensitivity is raised by the supersensitization.

It is another object of the present invention to provide an improvedsilver halide photographic emulsion wherein the red sensitivity is notgiven to an adjacent emulsion layer through diffusion when used as ared-sensitive emulsion layer of a color sensitive material.

SUMMARY OF THE INVENTION The above-mentioned objects of the presentinvention can be accomplished by incorporating in a silver halidephotographic emulsion a combination of at least one of the sensitizingdyes represented by the following general formula I and at least one ofthe sensitizing dyes represented by the following general formula II:

General Formula I wherein R, is an alkyl group having one to four carbonatoms, such as methyl and ethyl groups; R and R are individually analkyl group such as a methyl, ethyl or propyl group, an allyl group or asubstituted alkyl group such as 2-hydroxyethyl, 2- methoxyethyl,carboxymethyl, 2-carboxyethyl, 3-carboxypropyl, 4-carboxybutyl,3-sulfopropyl, 4-sulfobutyl, 3-sulfoisobutyl, 2-carboethoxyethyl,2-(3-sulfopropoxy)ethyl, 2[2- (3-sulfopropoxy)]ethoxyethyl and2-hydroxy-l-sulfopropyl groups; Z, and Z are the same or differentatomic groups necessary for forming a benzothiazole or benzoselenazolenucleus; n is l or 2 X is an acid anion group such as halide, rhodanate,perchlorate, p-toluene sulfonate, benzene-sulfonate, ethylsulfate,methylsulfate ion, etc., and

General Formula II wherein A is a thienyl group, a furyl group or asubstituted thienyl group such as 2,5-dichloro-3-thienyl,5-methyl-2-thienyl or 2-methyl-5-carboxy-3-thienyl; R and R areindividually an alkyl group, an allyl group or an alkyl groupsubstituted by a group selected from the group consisting of hydroxy,alkoxy, carboxy, sulfo, carboxy alkoxy and sulfoalkoxy, at least one ofR and R being a substituted alkyl group containing a sulfo group; 2;, isan atomic group necessary for forming a naphthothiazole or anaphthoselenazole nucleus and Z, is an atomic group necessary forforming a naphthothiazole, naphthoselenazole, benzothiazole orbenzoselenazole nucleus.

BRIEF DESCRIPTION OF THE DRAWING The FIGURE shows the sensitizationeffects of employing a dye of formula I alone, a dye of formula II aloneand a combination of dyes of formulas I and II, respectively.

DETAILED DESCRIPTION OF THE INVENTION The important features of thepresent invention are: I in the compound represented by the generalformula II, at least one of the two heterocyclic nuclei of the cyaninedye is a naphthoselenazole or a naphthothiazole nucleus, (2) there is atleast one sulfo-substituted alkyl group on the resonating terminalnitrogen atom in the heterocyclic nucleus and (3) there is either anaryl group, a thienyl group, a furyl group or a substituted thienylgroup in the meso position.

There are many cyanine dyes capable of giving characteristics similar tothe cyanine dyes of the present invention having an aryl group at themeso position. The sensitizing dye represented by general formula IIshows a very weak spectral (ID) 8 S sensitizing action only when usedalone, but a remarkably high (13H; spectral sensitivity when usedtogether with the sensitizing dye represented by general formula l. 1 g/Another feature of the present invention is that the maxi imumsensitizing wavelength is not migrated to longer than the 013,),8 0(011935 OQH- Nw Hm maximum sensitizing wavelength obtained by thesensitizing (11;) s s dye represented by the general formulas, ratherthere is a tendency of color dilution, a weak sensitivity within theCCH=CCH=C I wavelength region 680-690 mp, a high spectral sensitivity in01- --C1 the red region. The present invention is thus different in this1:1 N respect from that described in Japanese Pat. Publication No.($39105 5 ((iJHMOH 4933/ l 968. in accordance with the presentinvention, further- (HA) more, the particular dye employed is preventedfrom diffusing 15 S S S into an adjacent emulsion layer whereby the redsensitivity is not given, and accordingly the color reproduction isimproved.

The spectral sensitivity obtained by the use of a combinaf tion of thesensitizing dye represented by general formula I 0,11 (CHmS O and thesensitizing dye represented by general formula ll resists the hinderingaction of a coupler of the incorporated (HE) yp S s s The sensitizingdye represented by general formula I is a carbocyanine dye whose J-bandappears easily. The CCH=CCH=C benzothiazole nucleus or benzoselenazolenucleus may be substituted by a halogen atom, a phenyl group, an alkylgroup N or a hydroxyl group so that the J-band may appear easily or a((IIHMS l I suitable spectral sensitivity distribution may be given.

The sensitizing dyes used in the present invention are added to thesilver halide emulsion separately or in admixture in the form of asolution in water or in a water-soluble organic solvent such asmethanol, ethanol, acetone or pyridine. The amount added and the orderof addition to the silver halide (II C) emulsion may be varied asdesired. In general, the amount of Se 3 the sensitizing dye added ispreferably from 1X 10' to lXlO \Zl mole per mole of silver halide andthe weight ratio of sensitiz- J;

ing dye ll to sensitizing dye l is from l00:l to 1:10, preferably Clfrom 20:] to lzl. rtz N & Hg) 03- Any of the following may be used asthe silver halide emul- 4O tiling sion in the present invention: silverchloride, silver chlorobromide, silver bromide and silver iodobromide.The sensitizing dyes of the present invention may be incorporated intothe (H D) silver halide emuision together with a fog inhibitor, astabil- 45 izer, a chemical sensitizer, a hardener, a coupler, aplasticizer, 8 Se a photographic dye and a coating agent. 2

The thus-obtained silver halide photographic emulsion hav- C CH= mg theforegoing composition may be applied to a suitable Q support, forexample, a cellulose derivative film, polyethylene N N terephthalatefilm, other plastic films, baryta paper, resin 4,

. 1H5 coated paper, synthetic paper or a glass sheet.

Examples of the sensitizing dyes used in the present inven- Clix Thesensitizing dye of general formula I used in the present invention maybe synthesized by any known method, for example, that disclosed in U.S.Pat. No. 2,503,776 or German Pat. No. 929,080.

The sensitizing dye of general formula Il may be synthesized by anyknown method, for example, that disclosed in U.S. Pat. No. 2,060,383,U.S. Pat. No. 2,756,227 or U.S. Pat. No. 2,503,776.

Methods of synthesis of typical sensitizing dyes of the presentinvention are shown below:

Synthesis of dye (11A) CH=CC Synthesis of dye (HG) 0.5 of4,5-benzo-3-ethyl-2-(alpha-throfuroyl)methylenebenzothiazoline and 0.4g. of methyl ptoluenesulfonate are reacted for 1 hour by heating andfusing at 1 C. The reaction product is mixed with 0.4 g. of a anhydro2,5-dimethyl-3-(sulfopropyl)benzothiazolium hydroxide and reacted for 1hour in 30 ml. of ethanol and 1 ml. of triethylamine while heating andrefluxing. The precipitated crystal is filtered and recrystallized froma mixed solvent of methanol and chloroform to give 0.4 g. of a dye (llG) melting at 282 C. Spectral absorption maximum wavelength 607 my (inmethanol).

The following examples are given in order to further illustrate thepresent invention and are not intended to limit the same.

EXAMPLE 1 Five hundred grams of a silver iodobromide gelatin emulsion(silver iodobromide content 4.0 mole percent) prepared in a conventionalmanner was taken and rendered molten in a thermostat at 40 C. As shownin table 1, a predetermined amount of the sensitizing dye represented bygeneral formula l and a predetermined amount of the sensitizing dyerepresented by general formula II were mixed in solution and addedthereto with agitation.

The emulsion was allowed to stand in the thermostat at 37 C. whilestirring for 10 minutes, then uniformly coated onto a glass sheetsupport in a proportion of 7.0 ml. per cabinet size, set and dried toobtain a light-sensitive sample. The sample was cut and subjected tolight-wedge exposure using a red light from a light source having acolor temperature of 5,400 K. obtained by adapting a Davis-Gibsonconversion filter to a light source having a color temperature of 2,666K. and using a K-7 filter (made by Fuji Photo Film Co, Ltd.) permittingwavelengths longer than about 600 mg.

The exposed sensitive sample was developed at C. for 10 minutes with adeveloper having the following composition, stopped, fixed and washedwith water to obtain a strip. Measurement of the density thereof wascarried out by the use of an S-type densitometer made by Fuji Photo FilmCo., Ltd. to determine the relative red sensitivity. The optical densitypoint at which the sensitivity was determined was a point of (fogdensity +0.10). The results are shown in table 1.

S O S IE1 Composition of Developer water C.) 750 ml CH C CH melol 2 g. 1anhydrous sodium sulfite 100 g. N N hydroquinone 5 g. l 50 borax 2 g.CIHS HDQ f water to L000 ml.

pH=8.701-0.l0

sensitizing Amount used, sensitizing Amount used, Rel. red ASE dye ml.(mole cone.) dye ml. (mole cone.) sensitivity Fog mu. Note 10 (1x10 0.11650 20 0.13 650 Curve (1) in figure.

20 (1X10-' 5 166 0.17 650 20.... 10 200 0.17 650 Curve (3) in figure. 1(5X10- 30 0.12 695 Curve (2) in figure. 2 30 0. 14 695 1 A (1X10-") 1310.12 645 1 1 0.12 645 IID........10(5X10 21 0.10 685 20 25 0. 10 685 1 A20 (1x10 5 (5X10-) 126 0.10 645 20 10 0.11 645 sensitizing Amount used,sensitizing Amount used, Rel. red ASN.1. dye m1. (mole cone.) dye ml.(mole cone.) sensitivity Fog m Note 1 C 20 (x10*) B0 0.10 638 40 c 850.12 638 (5x10-) 100 0. 16 635 105 0.15 635 The light-sensitive emulsionsample half exposed was cut i d e u H h f Amount Amount Rel. p slng a reec grating p g p 9 0 used Sensiused red.

Sensltizln (mole tizln (mole sensilowed by a series of developingprocessings to obtain a spec dye 8 com.) dye 8 cont) mm, Fog xsmuntrogram. The results are shown in the accompanying graph for comparison.Curve 1 is a curve obtained by using 20 ml. of a E) 20 (5)00) 85 0410 2040 100 0.10 solution of (I A) having a mole concentration of 5X10 curve105 0.10 2 is a curve obtained by using 1 ml. of a solution of (ll B)havg8 g- F ing a mole concentration of 5M0, and curve 3 is a curve ob-0: 15 (ii iii tained byjointly using (l A) and (ll B). As is evidentfrom the g i; raph, the supersensitizing effect is marked. 25 3:}; 5) 00115111111: EXAMPLE 2 87 0.14 550 75 0.14 One thousand grams of a silveriodobromide gelatmg emulsion (silver iodobromide content 6 mole percent)prepared in isperctmily Sensmzed Very a convenuonal Tanner was mken andrendered mohen a ll will be understood from these results that thesensitizing q f at 37 example 1, a pf f amount dyes of the presentinvention have excellent properties as of sensitizing dye was addedthereto, stirring adequately and compared i i i i dye allowed to standat 37 C. for 60 minutes. sens tizing dye A w is l i d i shown Fl wasused for compaflson B laddmo" to l. A silver halide photographicemulsion containing at least the Sensmzmg dyes of the W mvemlon' onesensitizing dye represented by the following formula l:

Then 200 ml. of a 5 percent aqueous solution of cyan coupler B havingthe structure shown below was added thereto "W and stirred. A surfactantwas then added to the resulting emull I sion and the emulsion was coatedonto a cellulose triacetate G CH C CH*C (I) film to obtain ared-sensitive color photographic material. 40 f (X")n-i N Thephotographic material was subjected to light-wedge ex- R3 posure in amanner similar to example i, then to development at 20 C. for 12 minuteswith a color forming developer containing aN,N'diethylaminoparaaminoaniline derivative, first fixing, bleaching,second fixing and water washing to obtain a negative cyan image.Measurement of the red filter density was carried out by the use of ared filter to obtain a relative red sensitivity. The results are shownin table 2.

wherein R, is an alkyl group having from one to four carbon atoms; R andR are individually selected from the group consisting of an alkyl group,an allyl group and an alkyl group substituted by a hydroxyl group, analkoxyl group, a carboxyl group, a sulfo group, a carboxyalkoxyl group,or a sulfoalkoxyl group; Z, and 2 are the same or different atomicgroups ensitizing dye A (or comparison necessary to complete abenzothiazole nucleus or a l benzoselenazole nucleus; n is l or 2 and X18 an acid anion S S S group; and at least one sensitizing dyerepresented by the following formula ll: i //CCH=CCH=C l A? l i Z;C-CH=CCH=C'- Z4 (11) 0,111 0,115 I i 1'1. 1%. H3o-soi- 6Q wherein A is athienyl group, a fury] group or a thienyl group coupler B substituted bya halogen atom, an alkyl group or an alkyl car- OH boxyl group; R and R:are individually selected from the A group consisting of an alkyl group,an aryl group and an alkyl CONHCnHz-r group substituted by a hydroxylgroup, an alkoxyl group, a

carboxyl group, a sulfo group, a carboxyalkoxyl group or a sulfoalkoxylgroup; at least one of R and R being a sulfo-subl stituted alkyl group;2;, is an atomic group necessary to S OzNB complete a naphthothiazolenucleus or a naphthoselenazole Composition of Developer nucleus, and Zis an atomic group necessary to complete aN,N'-diethylaminoparaaminoaniline sulfate naphthothiazole nucleus, anaphthoselenazole nucleus, a Sodium 20 gbenzothiazole nucleus or abenzoselenazole nucleus.

sodium carbonate (monohydrate) 50 4 hydwxylamine hydrochloride L5 g 2. Asilver halide photographic emulsion as in claim 1,

potassium br L0 8 wherein said sensitizing dyes represented by formulasl and ll water to 1,000 ml. are:

Cl\) C1 5 zh f :)a a (C: s)z

and

CCH=C-CH=C l I I (1,115 i :)zB0a' respectively.

3. A silver halide photographic emulsion as in claim 1, where saidsensitizing dyes represented by formulas I and [I are:

S S z GOH=CCH=C C1 C1 2)a a :)a a r s)a and S Sc I CCH=CC.H=

i i i i can CH,(|JHSOr respectively.

4. A silver halide photographic emulsion as in claim 1,

where said sensitizing dyes represented by formulas l and ll are: 5

f Da f H=)as0=HN(0,H5);

and

I /CCH=CCH=C\ OCH; 7 (CHfigSOg (CH3)3SO3NB respectively. 5. A silverhalide photographic emulsion as in claim 1, where said sensitizing dyesrepresented by formulas l and II are.

s\ C H /s I 5 CCH=(ECH=C 01 01 (CHDSS s 2)aS a 2 s)z and .a.

6. A silver halide photographic emulsion as in claim 1, where saidsensitizing dyes represented by formulas l and ll are:

7. A silver halide photographic emulsion as in claim I, where saidsensitizing dyes represented by formulas l and ll I C H andrespectively.

8. A silver halide photographic emulsion as in claim I, where saidsensitizing dyes represented by formulas l and ll are:

wherein said weight ratio varies from 20:1 to lzl 11. A color sensitivematerial comprising a support having thereon at least one layercontaining the photographic silver halide emulsion as in claim 1.

2. A silver halide photographic emulsion as in claim 1, wherein saidsensitizing dyes represented by formulas I and II are:
 3. A silverhalide photographic emulsion as in claim 1, where said sensitizing dyesrepresented by formulas I and II are:
 4. A silver halide photographicemulsion as in claim 1, where said sensitizing dyes represented byformulas I and II are:
 5. A silver halide photographic emulsion as inclaim 1, where said sensitizing dyes represented by formulas I and IIare:
 6. A silver halide photographic emulsion as in claim 1, where saidsensitizing dyes represented by formulas I and II are:
 7. A silverhalide photographic emulsion as in claim 1, where said sensitizing dyesrepresented by formulas I and II are:
 8. A silver halide photographicemulsion as in claim 1, where said sensitizing dyes represented byformulas I and II are:
 9. A silver halide photographic emulsion as inclaim 1, wherein the amount of sensitizing dye added to said emulsionvaries from 1 X 106 to 1 X 10 3 mole per mole of silver halide, andwherein the weight ratio of said dye of formula II to said dye offormula I varies from 100:1 to 1:10.
 10. A silver halide photographicemulsion as in claim 9, wherein said weight ratio varies from 20:1 to1:1 .
 11. A color sensitive material comprising a support having thereonat least one layer containing the photographic silver halide emulsion asin claim 1.